US4830263A - Thermally stable polyoxyalkylene heat transfer fluids - Google Patents
Thermally stable polyoxyalkylene heat transfer fluids Download PDFInfo
- Publication number
- US4830263A US4830263A US06/933,133 US93313386A US4830263A US 4830263 A US4830263 A US 4830263A US 93313386 A US93313386 A US 93313386A US 4830263 A US4830263 A US 4830263A
- Authority
- US
- United States
- Prior art keywords
- daltons
- molecular weight
- polyether
- group
- solder
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G65/00—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule
- C08G65/02—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring
- C08G65/26—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring from cyclic ethers and other compounds
- C08G65/2639—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring from cyclic ethers and other compounds the other compounds containing elements other than oxygen, nitrogen or sulfur
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L71/00—Compositions of polyethers obtained by reactions forming an ether link in the main chain; Compositions of derivatives of such polymers
- C08L71/02—Polyalkylene oxides
Definitions
- the subject invention relates to polyoxyethylene polyethers which are thermally stable at high temperatures. These polyethers find special utility as heat transfer fluids and soldering auxiliaries.
- the circuit board, the components mounted thereon is partially immersed into a pot of molten solder, bonding the component leads to the foil conductors on the surface of the board.
- One of the disadvantages of the solder pot technique is the trapping of gas bubbles or debris under the surface of the board preventing the adherence of solder at these locations.
- a further disadvantage is the formation of an oxide coating, or dross, on the surface of the solder bath as a result of oxidation of the hot molten solder by atmospheric oxygen. The dross interferes with uniform soldering resulting in a high rejection rate of the finished boards.
- U.S. Pat. No. 3,054,174 describe the use of a high boiling fluid to bond leads to semi-conductor devices by immersing the devices with pre-positioned leads into the fluid. Suggested fluids are anhydrous lanolin, silicones, glycerine, ethylene glycol and polyethylene glycol.
- U.S. Pat. No. 3,214,827 discloses a process for soldering stacked printed circuit boards by immersion of the assembled, solder-coated components into a hot bath of fluid where solder reflow takes place. Corn oil is suggested as a suitable fluid.
- U.S. Pat. No. 3,690,943 discloses the use of a stationary wave of heat transfer fluid to alloy two or more metals on a printed circuit board.
- the hot fluid which may be selected from paraffins, fats, and mineral and vegetable oils, is pumped smoothly through a long but narrow orifice thereby forming a uniform wave of fluid.
- the previously metallized circuit board is passed through the wave at a speed appropriate to raise the temperature to a sufficient level so as to alloy the metals coated thereon.
- the wave soldering technique has become quite important commercially.
- a stationary wave of solder is formed in much the same manner as the wave of heat transfer fluid described in U.S. Pat. No. 3,680,943.
- the circuit board and mounted components are passed at a predetermined speed through the stationary wave of solder.
- the dross formed on the solder may be skimmed off as the solder is recirculated but nevertheless causes higher than desirable reject rates.
- thermally stable oils may be added to the wave soldering apparatus either in bulk or in continuously metered amounts. In addition to minimizing dross formation, these oils also have the advantage that they lower the surface tension of the solder, promoting more even solder coating.
- the processes described above utilize a high temperature liquid, generally termed an "oil” irrespective of its actual composition. Regardless of the particular application, the oil must fulfill several, often conflicting requirements. First and foremost, it must have superior thermal properties. Among the thermal properties most desirable are high boiling point (and correspondingly low volatility), high smoke point, and in particular, high thermal stability with regard to common high temperature chemical reactions such as pyrolysis and oxidation. Further, it should not deposit appreciable amounts of resinous residue upon the circuit boards, or produce large amounts of such residue, or sludge, upon long-term use.
- the oil should be non-reactive with the solder, the circuit board composition, and the electronic components. Finally, it is most desirable that the oil by easily and virtually completely removable by washing the inexpensive solvents, most preferably, water.
- polyoxyalkylene polyethers have been proposed for these uses.
- polyoxyethylene glycols were proposed for use in U.S. Pat. No. 3,054,184, discussed previously.
- these polyethers suffer from low thermal stability and therefore have not been used to any appreciable extent.
- Alkylphenol oxyethylates have been utilized by the industry, but still do not have thermal stability of the degree desired.
- An oil of improved thermal stability was disclosed in U.S. Pat. No. 4,360,144.
- These improved oils are heteric polyoxyalkylene polyethers initiated with bisphenol A, containing a 1:3 ratio of oxyethylene and oxypropylene residues in the polyoxyalkylene chains. Although these materials constituted a considerable advance over oils previously available in terms of thermal stability, further improvement is desirable. Furthermore, the bisphenol A initiated polyethers had less than the optimal degree of rinseability.
- a polyoxyalkylene polyether with superior thermal properties including high boiling point, high flashpoint and excellent thermal stability, combined with superior rinseability.
- Such a product is suitable for a variety of uses including, but not limited to, heat transfer fluids, solder reflow fluids, and wave soldering oils.
- polyoxyethylene polyethers initiated with an aromatic initiator molecule having two or more reactive hydrogens, wherein the active hydrogens are bonded to oxygen or nitrogen atoms located para to each other on the aromatic nucleus of the initiator molecule.
- These polyoxyalkylene polyethers possess excellent thermal properties and at the same time show excellent rinseability.
- the thermally stable cogeneric polyoxyethylene polyethers of the subject invention have the formula ##STR1## wherein each R radical is individually selected from the group consisting of hydrogen, fluoro, chloro, and lower alkyl having 1 to 4 carbon atoms, and wherein each X is individually selected from the group consisting of ##STR2## wherein n and m are integers greater than 2 such that the molecular weight of said polyether is from about 500 Daltons to about 10,000 Daltons.
- polyoxyalkylene polyethers are prepared by the ring-opening condensation polymerization of ethylene oxide onto a suitable initiator molecule. This process, generally referred to as oxyethylation, is generally accomplished through the use of catalysts.
- Lewis acid catalysts such as boron trifluoride etherate and aluminum chloride may be utilized as catalysts.
- basic catalysts such as sodium or potassium hydroxides, or sodium or potassium lower alkoxides are utilized, in amounts of from about 0.01 to 10 percent by weight based on the initiator weight.
- the oxyethylation is generally conducted at pressures greater than atmospheric and at temperatures of from 70° C. to 150° C., generally at about 105° to 135° C.
- the ethylene oxide may be added all at once, but it is preferable, for safety reasons, to add it gradually, or intermittently as previously added oxide reacts. It is possible to conduct the oxyethylation in the presence of minor amounts of higher alkylene oxides such as propylene oxide or butylene oxide to prepare a heteric copolymer polyether polyol.
- the thermal stability decreases with increasing content of the higher alkylene oxide, and thus it is desirable to minimize the amount of such higher alkylene oxide. Generally, more than 5 percent by weight significantly lowers the thermal stability.
- the amount of higher alkylene oxide is 3 percent or less. Most preferably, no higher alkylene oxide is present.
- the finished polyether after discharging from the reactor, may be treated or neutralized to remove the residual catalyst.
- the preferred basic catalysts may be removed by treatment with magnesium silicate, or they may be neutralized with inorganic acids such as phosphoric acid, or with organic acids such as acetic acid and salicylic acid.
- Suitable initiators which may be used to prepare the polyoxyethylene polyethers of the subject invention are substituted and unsubstituted benzenoid hydrocarbons having hydroxyl and/or amino functional groups located para to each other on the aromatic ring.
- Suitable initiators for example, are substituted or unsubstituted hydroquinones, p-phenylenediamines, and p-aminophenols. Particularly preferred are hydroquinone, p-phenylenediamine and p-aminophenol.
- the initiators are oxyethylated until the average molecular weight is between 500 and 10,000 Daltons and preferably between 500 and 5000 Daltons.
- the most preferred polyoxyethylene polyethers of the subject invention have molecular weights between 600 and 2000 Daltons.
- Polyethers of the subject invention in the lower molecular weight range possess greater thermal stability than their higher molecular weight analogues. However the volatility of the lower molecular weight products is greater as well. For these reasons, polyethers having molecular weights of about 1000 Daltons are especially preferred.
- the polyethers of the subject invention may be used alone, in the form of mixtures, or in conjunction with other oils and additives.
- the addition of nonylphenol oxyethylates to the subject polyoxyethylene polyethers allows the formulation of a less expensive product at some sacrifice of thermal stability and volatility. In general, it is not desirable to add more than 10 percent to 20 percent by weight of these less thermally stable polyethers to the polyoxyethylene polyethers of the subject invention.
- Oxidation inhibitors such as phenothiazine may also be added to the subject polyoxyethylene polyethers to further enhance thermal stability. In general, from 0.1 percent to 1 percent by weight of inhibitor is added when such additional stabilization is desired. Soldering additives, especially those which promote the even flow of solder and/or chemically clean the metallic surface may also be used. Long chain alkanoic acids are frequently added for this purpose, for example, stearic acid and oleic acid. Oleic acid is preferred. The organic acid is added in relatively small quantities, generally less than 10 percent by weight, and preferably less than 7 percent by weight. Improved stability may also be achieved generally by neutralizing the alkaline oxyethylation catalyst with organic acids such as acetic acid and allowing the resulting carboxylic acid salts to remain in the finished product.
- inorganic salts or rosin acids may also be added.
- the addition of these more active cleaning agents is especially desirable if the polyoxyethylene polyethers of the subject invention are to be utilized in solder fluxes, particularly in automatic, continuous fluxing operations.
- polyethers 1, 2, and 3 were synthesized and their properties compared to other polyoxyalkylene polyethers used in high temperature operations.
- Polyethers 1 and 2 are cogeneric polyoxyethylene polyethers having average molecular weights of about 1400 and 800, respectively. These polyethers were prepared by oxyethylating bis(2-hydroxyethyl)hydroquinone with 30 and 14 moles of ethylene oxide in the presence of potassium hydroxide catalyst. The requisite amount of ethylene oxide was added at less than 90 psig at a temperature of 140° C. The finished polyethers were discharged, treated with magnesium silicate, filtered, and stripped for one hour at 125° C. and 10 torr. Polyether 2P differs from polyether 2 in containing 0.5 percent by weight of phenothiazine.
- Polyether 3 is an 800 average molecular weight cogeneric polyoxyethylene polyether prepared by oxyethylating p-phenylenediamine with 16 moles of ethylene oxide in the presence of potassium hydroxide catalyst. The method of preparation was similar to that utilized above.
- Polyethers C-1 and C-1P are commercially available solder bath oils which are nonylphenol oxyethylates prepared by oxyethylating nonylphenol with 10 moles of ethylene oxide in the presence of potassium hydroxide catalyst.
- Polyether C-1P differs from C-1 in being stabilized with 0.5 percent phenothiazine.
- Polyethers C-2 and C-2P are commercially available polyethers which are butyl alcohol initiated heteric polyoxyethylene-polyoxypropylene copolymers having an average molecular weight of 4600 Daltons.
- Polyether C-2P differs from polyether C-2 in being stabilized with 0.5 percent phenothiazine.
- Polyether C-3 is a 1500 molecular weight polyoxyethylene polyether initiated with bisphenol A.
- Polyether C-4 is a 2000 molecular weight hydroquinone initiated heteric copolymer polyether containing 20 percent by weight of oxypropylene groups.
- Polyether C-5 is an 800 molecular weight polyoxyethylene polyether initiated with p-methylphenol.
- Table I shows that the polyethers of the subject invention have smoke points which are considerably higher than comparable, commercially available polyethers.
- thermal stability of various polyoxyalkylene polyethers is presented in Table II.
- 3 grams of each polyether was added to a petri dish and maintained in a circulating air oven at 232° C. for three hours.
- 24 hours the same quantities of polyethers were added to metal pans and maintained in the circulating air oven at 240° C. for 24 hours.
- the pan or dish was reweighed and the amount of polyether remaining expressed as a percentage of the initial amount.
- the thermal stability is proportional to the amount of polyether remaining.
- Table II shows convincingly that the polyoxythylene polyethers of the subject invention have significantly improved thermal stability over prior art commercial products such as comparative polyether C-1 and the all polyoxyethylene analog to the polyether of U.S. Pat. No. 4,360,144.
- Rinseability of various polyoxyalkylene polyethers is presented in Table III. To determine rinseability, a microscope slide was dipped into the liquid polyether, then dipped into water. The rinseability was measured by counting the number of seconds taken until clear upon visual inspection.
- Table III shows that products of the subject invention have superior rinseability as compared to prior art and commercial products.
Landscapes
- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Polyethers (AREA)
Abstract
Description
TABLE I ______________________________________ Polyether Smoke Point, °C. ______________________________________ 1 214 2 279 2P 283 3 226 C-1 207 C-2 185 C-4 205 C-5 170 ______________________________________
TABLE II ______________________________________ % Residue for % Residue % Residue Bulk Sample after 3 hrs. after 24 hrs. after 86 hrs. Polyether @ 232° C. @ 240° C. @ 232° C. ______________________________________ 1 99 55 91 2 99 51 -- 2P -- 57 92 C-1 93 2.5 53 C-1P -- 5.0 61 C-2 99 2.0 27 C-2P -- 2.0 22 C-3 93 46 -- C-4 -- 13.0 -- ______________________________________
TABLE III ______________________________________ Polyether Rinseability, seconds ______________________________________ 1 2 2 2* C-1 13 C-2 39 C-3 25 ______________________________________ *best rinseability of all candidates tested.
Claims (24)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US06/933,133 US4830263A (en) | 1985-05-09 | 1986-11-21 | Thermally stable polyoxyalkylene heat transfer fluids |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US73240485A | 1985-05-09 | 1985-05-09 | |
US06/933,133 US4830263A (en) | 1985-05-09 | 1986-11-21 | Thermally stable polyoxyalkylene heat transfer fluids |
Related Parent Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US73240485A Division | 1985-05-09 | 1985-05-09 |
Publications (1)
Publication Number | Publication Date |
---|---|
US4830263A true US4830263A (en) | 1989-05-16 |
Family
ID=27112396
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US06/933,133 Expired - Lifetime US4830263A (en) | 1985-05-09 | 1986-11-21 | Thermally stable polyoxyalkylene heat transfer fluids |
Country Status (1)
Country | Link |
---|---|
US (1) | US4830263A (en) |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5381945A (en) * | 1991-02-01 | 1995-01-17 | Leicht; Helmut W. | Process for soldering materials like printed circuit boards or sets of components in electronics or metals in engineering work |
US5545440A (en) * | 1994-12-05 | 1996-08-13 | At&T Global Information Solutions Company (Aka Ncr Corporation) | Method and apparatus for polymer coating of substrates |
US20030213833A1 (en) * | 2000-12-21 | 2003-11-20 | Fujitsu Limited | Reflow soldering apparatus and reflow soldering method |
US20060192173A1 (en) * | 2005-02-25 | 2006-08-31 | Sunkara Hari B | Process for heat transfer utilizing a polytrimethylene homo- or copolyether glycol based heat transfer fluid |
EP1978077A1 (en) * | 2007-03-29 | 2008-10-08 | FUJIFILM Corporation | Lubricant composition, mechanical element, and method for producing triazine derivatives |
CN106750247A (en) * | 2016-12-28 | 2017-05-31 | 三江化工有限公司 | A kind of preparation method of low free alcohol AEO |
Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4059218A (en) * | 1974-12-23 | 1977-11-22 | Allegheny Ludlum Industries, Inc. | Method of soldering with phosphoric acid soldering flux |
US4334646A (en) * | 1980-04-17 | 1982-06-15 | Harris Corporation | Method of solder reflow assembly |
US4360144A (en) * | 1981-01-21 | 1982-11-23 | Basf Wyandotte Corporation | Printed circuit board soldering |
US4376868A (en) * | 1980-02-14 | 1983-03-15 | Conoco Inc. | Alkoxylation of cresylic acids |
US4588840A (en) * | 1982-04-26 | 1986-05-13 | The Dow Chemical Company | Oxyalkylene aromatic amines |
US4591088A (en) * | 1983-05-31 | 1986-05-27 | Hughes Aircraft Company | Solder reflow process for soldering shaped articles together |
DE3615092A1 (en) * | 1985-05-09 | 1986-11-13 | Basf Corp., Parsippany, N.J. | Thermally stable polyoxyalkylene heat-transfer fluids |
-
1986
- 1986-11-21 US US06/933,133 patent/US4830263A/en not_active Expired - Lifetime
Patent Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4059218A (en) * | 1974-12-23 | 1977-11-22 | Allegheny Ludlum Industries, Inc. | Method of soldering with phosphoric acid soldering flux |
US4376868A (en) * | 1980-02-14 | 1983-03-15 | Conoco Inc. | Alkoxylation of cresylic acids |
US4334646A (en) * | 1980-04-17 | 1982-06-15 | Harris Corporation | Method of solder reflow assembly |
US4360144A (en) * | 1981-01-21 | 1982-11-23 | Basf Wyandotte Corporation | Printed circuit board soldering |
US4588840A (en) * | 1982-04-26 | 1986-05-13 | The Dow Chemical Company | Oxyalkylene aromatic amines |
US4591088A (en) * | 1983-05-31 | 1986-05-27 | Hughes Aircraft Company | Solder reflow process for soldering shaped articles together |
DE3615092A1 (en) * | 1985-05-09 | 1986-11-13 | Basf Corp., Parsippany, N.J. | Thermally stable polyoxyalkylene heat-transfer fluids |
Cited By (13)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5381945A (en) * | 1991-02-01 | 1995-01-17 | Leicht; Helmut W. | Process for soldering materials like printed circuit boards or sets of components in electronics or metals in engineering work |
US5545440A (en) * | 1994-12-05 | 1996-08-13 | At&T Global Information Solutions Company (Aka Ncr Corporation) | Method and apparatus for polymer coating of substrates |
US20030213833A1 (en) * | 2000-12-21 | 2003-11-20 | Fujitsu Limited | Reflow soldering apparatus and reflow soldering method |
US6971571B2 (en) * | 2000-12-21 | 2005-12-06 | Fujitsu Limited | Reflow soldering apparatus and reflow soldering method |
US7476332B2 (en) | 2005-02-25 | 2009-01-13 | E.I. Du Pont De Nemours & Company | Heat transfer systems utilizing a polytrimethylene homo- or copolyether glycol based heat transfer fluid |
US7413677B2 (en) | 2005-02-25 | 2008-08-19 | E. I. Du Pont De Nemours And Company | Process for heat transfer utilizing a polytrimethylene homo- or copolyether glycol based heat transfer fluid |
US20080245993A1 (en) * | 2005-02-25 | 2008-10-09 | E. I. Dupont De Nemours And Company | Heat transfer systems utilizing a polytrimethylene homo- or copolyether glycol based heat transfer fluid |
US20060192173A1 (en) * | 2005-02-25 | 2006-08-31 | Sunkara Hari B | Process for heat transfer utilizing a polytrimethylene homo- or copolyether glycol based heat transfer fluid |
EP1978077A1 (en) * | 2007-03-29 | 2008-10-08 | FUJIFILM Corporation | Lubricant composition, mechanical element, and method for producing triazine derivatives |
US20080274920A1 (en) * | 2007-03-29 | 2008-11-06 | Fujifilm Corporation | Lubricant composition, mechanical element, and method for producing triazine derivatives |
US7956020B2 (en) | 2007-03-29 | 2011-06-07 | Fujifilm Corporation | Lubricant composition, mechanical element, and method for producing triazine derivatives |
CN106750247A (en) * | 2016-12-28 | 2017-05-31 | 三江化工有限公司 | A kind of preparation method of low free alcohol AEO |
CN106750247B (en) * | 2016-12-28 | 2018-03-06 | 三江化工有限公司 | A kind of preparation method of low free alcohol AEO |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US4360144A (en) | Printed circuit board soldering | |
KR101163427B1 (en) | Flux for lead-free solder and method of soldering | |
US5393448A (en) | Aqueous electronic circuit assembly cleaner and method | |
US5397495A (en) | Stabilization of silicate solutions | |
US5433885A (en) | Stabilization of silicate solutions | |
RU2372175C2 (en) | Method of soldering with soft solder | |
US4830263A (en) | Thermally stable polyoxyalkylene heat transfer fluids | |
US4028143A (en) | Wax-flux composition containing a succinimide salt of an alkylaryl sulfonic acid for soldering | |
US5264046A (en) | Aqueous electronic circuit assembly cleaner and cleaning method | |
JPH0149599B2 (en) | ||
US4514315A (en) | Aluminum corrosion inhibitor comprising alkylene-silane graft copolymer | |
US5141662A (en) | Heat transfer fluids comprising oxyalkylenated polyols | |
CA1255700A (en) | Thermally stable polyoxyalkylene heat transfer fluids | |
US3977916A (en) | Wax-flux composition containing alkylaryl sulfonic acid for soldering | |
USRE35045E (en) | Method for removing soldering flux with alkaline metal carbonate salts and an alkali metal silicate | |
EP0173167B1 (en) | Nonfuming solder cleansing and fusing fluids | |
US3960614A (en) | Wax-flux composition containing a diester of sulfomaleic acid for soldering | |
US6602833B1 (en) | Mechanical working in the presence of a metal containing copper or aluminum | |
USRE35017E (en) | Method for removing soldering flux with alkaline salts, an alkali metal silicate and anionic polymer | |
USRE35115E (en) | Low foaming effective hydrotrope | |
JPS63286291A (en) | Alkylene oxide addition product as flux and remelting liquid in manufacture of conductor board | |
CN111542648A (en) | Composition and etching method | |
CN114908341B (en) | Special surface treating agent for PCB chemical nickel-palladium-gold plating layer and preparation method thereof | |
SU1676775A1 (en) | Flux for melting electroplated coatings | |
KR102596167B1 (en) | Solder alloys and solder fittings |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: BASF CORPORATION, 1419 BIDDLE AVENUE, WYANDOTTE, M Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:DEXHEIMER, EDWARD M.;REEL/FRAME:004908/0390 Effective date: 19880628 Owner name: BASF CORPORATION,MICHIGAN Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:DEXHEIMER, EDWARD M.;REEL/FRAME:004908/0390 Effective date: 19880628 |
|
STCF | Information on status: patent grant |
Free format text: PATENTED CASE |
|
FEPP | Fee payment procedure |
Free format text: PAYOR NUMBER ASSIGNED (ORIGINAL EVENT CODE: ASPN); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY |
|
FPAY | Fee payment |
Year of fee payment: 4 |
|
FEPP | Fee payment procedure |
Free format text: PAYOR NUMBER ASSIGNED (ORIGINAL EVENT CODE: ASPN); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY Free format text: PAYER NUMBER DE-ASSIGNED (ORIGINAL EVENT CODE: RMPN); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY |
|
FPAY | Fee payment |
Year of fee payment: 8 |
|
FPAY | Fee payment |
Year of fee payment: 12 |
|
REMI | Maintenance fee reminder mailed |